A lawn rake is one of the most used tools for cleaning the yard from tree leaves and other debris in household and commercial lots. It has been designed and re-invented in a plethora of shapes, forms, and functionalities. Inventors throughout the past and present century have strived to come up with many improvements to its design for the purpose of increasing efficiency, lowering cost, and expanding functionality.
The most common form of the lawn rake is configured as a single row of tines as disclosed in a number of U.S. patents such as U.S. Pat. Nos. 3,724,188; 4,189,908; 4,215,528; 4,219,993; 4,831,815; 4,848,073; 5,022,221; 5,177,947; 5,487,260 and 6,032,447. Such prior art perform reasonably well for leaves and debris that are large enough to span more than one rake tine and settle at the top of the lawn surface. On the other hand, there are many types of tree leaves such as, for example, Live Oak leaves that are short and narrow enough where they do not span more than one rake tine space. Moreover, such leaves are small enough to allow them to embed within the grass blades instead of settling only at the top of the lawn. Raking such leaves using the aforementioned prior art is very cumbersome and time consuming due to the inability of the rake to prevent the leaves from passing through the tines, as well as the inability of the rake tines to effectively sweep the embedded leaves. This failure to effectively collect the leaves would necessitate multiple sweeps to clean the same area. In addition, the flexibility that is designed into the rake tines of a prior art lawn rake causes the tines to slide over the embedded small leaves and only stir the leaves up in the air to subsequently fall back on the grass behind the rake stroke as shown in FIG. 1 and explained in detail in subsequent sections.
Attempts at improving the raking efficiency are cited in U.S. patents such as U.S. Pat. Nos. 3,264,810; 4,150,528; 4,351,145; 4,744,208; 5,099,638; 5,177,946; 5,249,413; 5,511,370 and 6,381,938.
Lowell, in U.S. Pat. No. 3,264,810 (1966) shows a comb is used to sweep the debris, such as acorns, as the rake is configured in such a way that its tines slide on their back side to act as a mulch compactor. This reduces the efficiency to that of a single row rake.
Rendin, in U.S. Pat. No. 4,150,528 (1979); Farkas, in U.S. Pat. No. 4,351,145 (1982); King, in U.S. Pat. No. 4,744,208 (1988); Bass, in U.S. Pat. No. 5,099,638 (1992); Dietz, in U.S. Pat. No. 5,177,946 (1993); McDonough, in U.S. Pat. No. 5,249,413 (1993); Patel, in U.S. Pat. No. 5,511,370 (1996) and Kelly, in U.S. Pat. No. 6,381,938 (2002) all use a multiple-row configuration of tines. Although better than a single-row configuration, the multiple-row configuration has several drawbacks. The leaves that pass through the first row of tines accumulate between the first and the second row of tines which will cause the second row of tines to become ineffective in interacting with the surface being raked. Another drawback is that the increase in the number of tines, as cited in U.S. Pat. Nos. 4,744,208; 5,177,946 and 6,381,938 requires that the operator exert a higher pressure on the surface being raked in order to achieve the same tine effectiveness in interacting with the surface, and to de-embed the small leaves from the grass. Furthermore, in all of the three designs, the angle of the tine ends makes them more likely to skip over the leaves and stir them up rather than scraping them off the grass. Yet another drawback is that the operation of the rake can be cumbersome and awkward due to the extra weight and the complicated design as cited in U.S. Pat. No. 5,249,413.
The device shown in U.S. Pat. No. 4,828,690 (1989) intends to sift through debris in the soil and sand used in the garden and may not be suitable, in its form and function, for leaf raking.
In yet other attempts to improve raking efficiency, U.S. Pat. Nos. 1,509,369; 2,099,053; 6,526,737 utilize removable attachments to incorporate and co-act with existing commercial rakes.
McKesson, in U.S. Pat. No. 1,509,369 (1924) uses a corrugated sheet metal that is inserted between the rake tines for the purpose of, amongst other additional functionalities, aiding in the raking action of small debris. For this attachment to work as described, it must be used with non-flexible tine rake, which is typically not suitable for raking leaves on lawns.
Donnan, in U.S. Pat. No. 2,099,053 (1937) uses a curved attachment that is installed directly on the rigid tines of a garden rake to effectively convert the garden rake into a hoe with a toothed edge. While the attachment is positioned to catch small leaves or other debris that pass between the tines, the position of the attachment relative to the rake tines leaves little space to collect small leaves and other debris. The other feature presented is the creation of vacuum behind the attachment which is claimed to help in pulling the light debris along with the rake. Even though in theory vacuum is created, it would not be sufficient to pull the heavier lawn debris effectively and completely. In addition, this feature becomes ineffective in the presence of wind.
Martin, in U.S. Pat. No. 6,526,737 (2003) shows a rake attachment that converts a rigid-tined garden rake into a garden hoe which is not suitable for raking grass leaves.